/*
 * This file is part of the OWL API.
 *
 * The contents of this file are subject to the LGPL License, Version 3.0.
 *
 * Copyright (C) 2011, Clark & Parsia, LLC
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see http://www.gnu.org/licenses/.
 *
 *
 * Alternatively, the contents of this file may be used under the terms of the Apache License, Version 2.0
 * in which case, the provisions of the Apache License Version 2.0 are applicable instead of those above.
 *
 * Copyright 2011, Clark & Parsia, LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.clarkparsia.owlapi.explanation;

import java.util.Set;

import org.semanticweb.owlapi.model.OWLAxiom;
import org.semanticweb.owlapi.model.OWLClassExpression;

/**
 * a generator for explanations
 */
public interface ExplanationGenerator {

    /**
     * Returns a single explanation for the given unsatisfiable class.
     * @param unsatClass The class that is unsatisfiable for which an explanation
     * will be generated.
     * @return A single explanation for the given unsatisfiable class, or
     *         empty set if the concept is satisfiable
     */
    public Set<OWLAxiom> getExplanation(OWLClassExpression unsatClass);


    /**
     * Returns all the explanations for the given unsatisfiable class.
     * @param unsatClass The class that is unsatisfiable for which an explanation
     * will be generated.
     * @return All explanations for the given unsatisfiable class, or an empty
     *         set if the concept is satisfiable
     */
    public Set<Set<OWLAxiom>> getExplanations(OWLClassExpression unsatClass);


    /**
     * Return a specified number of explanations for the given unsatisfiable
     * class. A smaller number of explanations can be returned if there are not
     * as many explanations for the given concept. The returned set will be
     * empty if the given class is satisfiable,
     * @param unsatClass The class that is unsatisfiable for which an explanation
     * will be generated.
     * @param maxExplanations Maximum number of explanations requested, or 0 to get all the
     * explanations
     * @return A specified number of explanations for the given unsatisfiable
     *         class, or an empty set if the concept is satisfiable
     */
    public Set<Set<OWLAxiom>> getExplanations(OWLClassExpression unsatClass, int maxExplanations);
}
